A nonvolatile memory having a stacked body in which insulating films and conductive films are alternately stacked as a memory cell array of a three-dimensional structure stacked in a height direction of the stacked body is being developed. Such a memory cell of the nonvolatile memory is provided between the stacked body and a columnar portion extending in a stack direction. A plurality of memory cells provided along the columnar portion are electrically connected in series and configure a memory string.
A tap region is provided for transferring a source voltage, a signal, a power source voltage, and the like to the memory cell, between cell regions of such a memory cell array. A contact plug in the tap region penetrates the stacked body and is connected to a source layer or a lower layer wiring under the source layer. For example, the contact plug connected to the lower layer wiring is adjacent to the source layer through an oxide film provided on an inner wall of a contact hole, and is connected to the lower layer wiring in a state in which the contact plug is electrically separated from the source layer by the oxide film.
The source layer may be provided entirely under the memory cell array in order to provide a source potential to the memory string. According to such a configuration, in a case where the oxide film is broken and current leakage occurs between the contact plug and the source layer, there may be a danger of irreparable failure of the whole device.